The current trend in connector design for those connectors utilized in the computer field is to provide both high density and high reliability connections between various circuit devices which form important parts of the computer. High reliability for such connections is essential due to potential end product failure, should vital misconnections of these devices occur. Further, to assure effective repair, upgrade, and/or replacement of various components of the system (i.e., connectors, cards, chips, boards, modules, etc.), it is also highly desired that such connections be separable and reconnectable in the field within the final product, as well as tolerant of dust and fibrous debris Such a capability is also desirable during the manufacturing process for such products, e.g., to facilitate testing.
One prior technique for providing various interconnections is referred to as a wire bond technique, which involves the mechanical and thermal compression of a soft metal wire, e.g., gold, from one circuit to another Such bonding, however, does not lend itself readily to high density connections because of possible wire breakage and accompanying mechanical difficulty in wire handling Another technique involves strategic placement of solder balls or the like between respective circuit elements, e.g., pads, and reflowing the solder to effect interconnection. While this technique has proven extremely successful in providing high density interconnections for various structures, this technique does not allow facile separation and subsequent reconnection. In yet another technique, an elastomer has been used which included therein a plurality of conductive paths, e.g., small diameter wires or columns of conductive material, to provide the necessary interconnections. Known techniques using such material typically possess the following deficiencies: (1) high force necessary per contact which can be inherent in a particular design and exacerbated due to non-planarity of the mating surfaces; (2) relatively high electrical resistance through the interconnection between the associated circuit elements, e.g., pads; (3) sensitivity to dust, debris and other environmental elements which could readily adversely affect a sound connection; and (4) limited density, e.g., due to physical limitations of particular connector designs. Such prior art elastomeric structures also typically fail to provide effective wiping connections, which form of connection is highly desirable in many high density interconnection schemes.
Attention is directed to U.S. Pat. Nos. 3,960,423, 3,960,424, 4,295,700, 4,636,018, 4,655,519, 4,793,814 and 5,049,084 for various techniques for providing electrical interconnections for a variety of electrical circuit members. As understood from a reading of these patents, the techniques as described therein include many of the aforedefined disadvantages, e.g., non-repeatability, potential misalignment, low density, etc. as well as others, e.g., relatively complex design, costly to manufacture, etc.
In U.S. Pat. No. 5,061,192, assigned to the same assignee as the present invention, there is defined an electrical connector for interconnecting a pair of circuit members (e.g., circuit, module and printed circuit board) which assures highly reliable, yet separable connections for these members. The connector includes an electrically insulative (e.g., plastic) frame which defines an internal opening therein. Bridging this opening are a plurality of individual, resilient contact members which are maintained in a suspended and spaced orientation within the opening by a plurality of pairs of elongated insulative members (e.g., polymer rods). Each of the contacts is thus removable from the connector's frame to facilitate repair and/or replacement. As described, the connector is capable of providing wiping connections, thus assuring removal of debris or other contaminants from the respective conductive pads for each circuit member. In another embodiment, the connector includes a common carrier (e.g., plastic) having therein a plurality of cylindrical shaped resilient contact members (e.g., silicone) which further include a quantity of conductive (e.g., metallic) particles therein. To assure a wiping form of engagement with the respective conductive pads, each of the terminal ends of each contact member preferably includes a plurality of dendritic, interdigitated members thereon. This patent is incorporated herein by reference.
It is believed that a method of making a flexible circuit member having conductive end portions as defined herein which is capable of being utilized in an electrical connector capable of providing effective, reliable connections (including providing a wiping type of connection), wherein such connections may be repeatable (such that connection and reconnection can readily occur), and which provides the other advantageous features discernible from the following description, would constitute a significant advancement in the art. It is also understood that a flexible circuit having conductive end portions made in accordance with the teachings herein is adaptable for use in other types of connectors and the invention is thus not limited to the particular connector defined in the above-cited co-pending application.